In the manufacture of plastic covered glass containers of the type disclosed in U.S. Pat. No. 3,760,968, glass containers at elevated temperature are conveyed in vertical upright position by a ware handling conveyor in single file past a sleeve making apparatus. The sleeve making apparatus receives a continuous web of pre-printed plastic, preferably a foamed polystyrene or foamed polyethylene, and from the web supply cuts successive lengths of the material and feeds the lengths to individual cylindrical mandrels. The mandrels are disposed on a movable turrent of the machine with their central axes disposed vertically. Each length of the plastic is wrapped around the periphery of the mandrel so that the leading and trailing ends overlap whereat they are united, or firmly attached to each other to form a cylindrical sleeve. The mandrels of the sleeve making apparatus move in registry with the containers on the ware handling conveyor in an assembly station over a span of travel whereat the sleeves are stripped axially from the mandrel by a stripper mechanism and telescopically assembled onto the glass container. Thereafter, the stripper mechanism retracts from the sleeve leaving the latter to be carried with the glass container to a heat shrinking apparatus, usually in the form of a tunnel-like oven chamber.
Various means have been devised for assuring that the sleeve will remain in the telescopically assembled position on the container until shrunken snugly thereon in the heat shrinking apparatus, the sleeve making machine and heat shrinking oven being spaced apart a distance over which the container and sleeve thereon must travel until shrinking of the sleeve begins. One such means is disclosed in the copending application of R. A. Ashcroft, U.S. Ser. No. 464,224 filed Apr. 25, 1974, of common ownership with the present application, and which is now U.S. Pat. No. 3,959,065. The Ashcroft device includes a heat tacking means which zonally shrinks an annular band portion of the plastic sleeve just as the sleeve and container are assembled such that the shrunken band portion holds the sleeve in place until the container reaches the shrinking oven. In the manufacture of glass containers covered with a heat shrunken thermoplastic sleeve, specific forms being a foamed polyethylene, foamed-film laminate of polyethylene, or foamed polystyrene and a film of ethylene ethyl acrylate laminated on the exterior of the foam, some difficulty is experienced in zonally shrinking a portion of the sleeve in the time and distance available to maintain the assembly of the sleeve on the container. It should be pointed out that shrinkable polyethylene material, and perhaps some other polyolefins, have a tendency under application of heat to first become very limp and actually grow or expand as a sleeve form before shrinkage occurs. With this in mind, the polyethylene sleeve will often enlarge upon initial heating such that it will fall from position on the container.